RRC3 Data Analysis Help, ie "What the Heck?"

[nute]

Hello all. I flew my 3" Aerobee Hi today on an I284W. Beautiful flight. After the flight the RRC3 beeped out 3733 feet. Exactly what the sims predicted. When I transferred the data to my PC I looked at the velocity data, which shows a peek velocity of 727 mph! :y:. Well that doesn't sound right. I thought maybe it was a units issue, but both the RRC3 and the mDACS are set to mph. Very strange, since it was only simming to 550 mph. On its last flight, the velocity was simming at 430 mph, and it recorded about 480. Okay, not too bad, but I'm really puzzled on this one. Anyone have any ideas?

Here's the graph from the RRC3:

And the file:
View attachment Aerobee Hi I284W 4-16-16.rff


I notice that weird "knee" in the velocity graph at around 3.5 s, and similarly can't explain it. Maybe gravity switched off for a few seconds?
So, data junkies, what's your analysis?


Thanks,
Nate

 

[Coop]

I know you said mDACS is configured to MPH, but it appears to be displaying ft/sec.

727 ft/sec = 495ish MPH. That would be in the ballpark of the 480 you were reporting...

I've no explanation for the thrust curve, not being familiar with the motor or rocket... could it be a dual-thrust job, where is dumps like mad, then tapers off?


Later!

--Coop

 

[watermelonman]

Barometric altimeter, velocity.

 

[DizWolf]

agreed. Baro just reads velocity poorly sometimes.

This was an I600 flight in Emerald Dragon, a 4" rocket that's had several flights that do not display this blip.